tarek99 wrote:

Is x+y less than 1?

(1) x is less than 8/9

(2) y is less than 1/8

Please explain your answer

Give the fractions the same denominator

X < 8/9

Y < 1/8

Test it out using this same denominator. Remember that X must be LESS than 64/72 and Y must be LESS than 9/72. Using 72 as a denominator these are the largest fractions we can use unless we expand out from integers (and get into 63.99/72 sort of thing)

Now many people might stop here and say that C is sufficient. Let's use a larger denominator so we can do more precise tuning and see what happens.

X <

and

Y <

These fractions are the same as the one above, we just multiplied the top and bottom by 10. Now let's take the largest fractions we can get and add them together like we did above:

As you can see, this fraction is larger than 1. Making both statements together insufficient.

Answer E